不韋 呂 / DSP_MultirateLinearphase

STM32F446 内蔵の DAC から出力する際に，補間フィルタを利用し，標本化周波数を入力の際の４倍の標本化周波数で出力するためのライブラリ．このライブラリを登録した際のプログラム： Demo_DSP_ADDA_Multirate. Library for outputting from built-in DAC in STM32F446 using interpolation filter at sampling frequency of 4 times in case of input.

Dependencies:   Array_Matrix DSP_ADDA

Dependents:   Demo_DSP_ADDA_Multirate DSP_AD_DA_Multirate DSP_GraphicEqualizerB DSP_VariableLHpfB ... more

MultirateLiPh.cpp@4:c233f2db4652, 2020-06-18 (annotated)

Committer:
MikamiUitOpen
Date:
Thu Jun 18 05:06:42 2020 +0000
Revision:
4:c233f2db4652
Parent:
3:59af3dfa0595
Child:
8:356d0c5f97c3
5

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 0:79c0b1e2fd10 1 //-----------------------------------------------------------
MikamiUitOpen 0:79c0b1e2fd10 2 // 出力を 4 倍にアップサンプリングするクラス
MikamiUitOpen 0:79c0b1e2fd10 3 // 補間処理で使うフィルタとして，直線位相 FIR フィルタを使用
MikamiUitOpen 0:79c0b1e2fd10 4 //
MikamiUitOpen 4:c233f2db4652 5 // 2020/06/18, Copyright (c) 2020 MIKAMI, Naoki
MikamiUitOpen 0:79c0b1e2fd10 6 //-----------------------------------------------------------
MikamiUitOpen 0:79c0b1e2fd10 7
MikamiUitOpen 0:79c0b1e2fd10 8 #include "MultirateLiPh.hpp"
MikamiUitOpen 0:79c0b1e2fd10 9
MikamiUitOpen 4:c233f2db4652 10 namespace Mikami
MikamiUitOpen 4:c233f2db4652 11 {
MikamiUitOpen 4:c233f2db4652 12 // コンストラクタ（デフォルトの補間フィルタの係数を使う場合）
MikamiUitOpen 4:c233f2db4652 13 MultirateLiPh::MultirateLiPh(float fSampling,
MikamiUitOpen 4:c233f2db4652 14 PinName pin, ADC_TypeDef* const adc)
MikamiUitOpen 4:c233f2db4652 15 : indexW_(0), FIR_LOOP_(ORDER_/4), CENTER_(ORDER_/(FACTOR_*2)),
MikamiUitOpen 4:c233f2db4652 16 un_(ORDER_/4, 0.0f),
MikamiUitOpen 4:c233f2db4652 17 h1_(ORDER_/4, HK1_), h2_(ORDER_/4, HK2_), h3_(ORDER_/4, HK3_)
MikamiUitOpen 4:c233f2db4652 18 { Init(fSampling, pin, adc); }
MikamiUitOpen 3:59af3dfa0595 19
MikamiUitOpen 4:c233f2db4652 20 // コンストラクタ（デフォルト以外の補間フィルタの係数を使う場合）
MikamiUitOpen 4:c233f2db4652 21 MultirateLiPh::MultirateLiPh(float fSampling, int order,
MikamiUitOpen 4:c233f2db4652 22 const float hk1[], const float hk2[],
MikamiUitOpen 4:c233f2db4652 23 const float hk3[],
MikamiUitOpen 4:c233f2db4652 24 PinName pin, ADC_TypeDef* const adc)
MikamiUitOpen 4:c233f2db4652 25 : indexW_(0), FIR_LOOP_(order/4), CENTER_(order/(FACTOR_*2)),
MikamiUitOpen 4:c233f2db4652 26 un_(order/4, 0.0f),
MikamiUitOpen 4:c233f2db4652 27 h1_(order/4, hk1), h2_(order/4, hk2), h3_(order/4, hk3)
MikamiUitOpen 4:c233f2db4652 28 { Init(fSampling, pin, adc); }
MikamiUitOpen 0:79c0b1e2fd10 29
MikamiUitOpen 4:c233f2db4652 30 // 標本化の実行開始
MikamiUitOpen 4:c233f2db4652 31 void MultirateLiPh::Start(void (*Func)())
MikamiUitOpen 4:c233f2db4652 32 {
MikamiUitOpen 4:c233f2db4652 33 // CAN2_TX によるソフトウェア割り込みに対応する設定
MikamiUitOpen 4:c233f2db4652 34 NVIC_SetVector(CAN2_TX_IRQn, (uint32_t)Func);
MikamiUitOpen 4:c233f2db4652 35 NVIC_EnableIRQ(CAN2_TX_IRQn);
MikamiUitOpen 0:79c0b1e2fd10 36
MikamiUitOpen 4:c233f2db4652 37 // AD 変換器を使うための準備
MikamiUitOpen 4:c233f2db4652 38 wait_us(1000); // ある程度の待ち時間が必要
MikamiUitOpen 4:c233f2db4652 39 adc_->SetIntrVec(&MultirateLiPh::AdcIsr); // AD 変換終了に対応する ISR の設定
MikamiUitOpen 4:c233f2db4652 40 }
MikamiUitOpen 0:79c0b1e2fd10 41
MikamiUitOpen 4:c233f2db4652 42 // 補間用フィルタを実行し，処理結果を出力用バッファへ書き込む
MikamiUitOpen 4:c233f2db4652 43 void MultirateLiPh::Output(float yn)
MikamiUitOpen 4:c233f2db4652 44 {
MikamiUitOpen 4:c233f2db4652 45 un_[0] = yn; // 補間フィルタ用バッファの先頭に書き込む
MikamiUitOpen 0:79c0b1e2fd10 46
MikamiUitOpen 4:c233f2db4652 47 buf_[ModIndex(indexW_)] = un_[CENTER_];
MikamiUitOpen 4:c233f2db4652 48 buf_[ModIndex(indexW_)] = Interpolator(h1_);
MikamiUitOpen 4:c233f2db4652 49 buf_[ModIndex(indexW_)] = Interpolator(h2_);
MikamiUitOpen 4:c233f2db4652 50 buf_[ModIndex(indexW_)] = Interpolator(h3_);
MikamiUitOpen 0:79c0b1e2fd10 51
MikamiUitOpen 4:c233f2db4652 52 for (int k=FIR_LOOP_-1; k>0; k--) un_[k] = un_[k-1];
MikamiUitOpen 4:c233f2db4652 53 }
MikamiUitOpen 0:79c0b1e2fd10 54
MikamiUitOpen 4:c233f2db4652 55 // ADC 変換終了割り込みに対する割り込みサービス･ルーチン
MikamiUitOpen 4:c233f2db4652 56 void MultirateLiPh::AdcIsr()
MikamiUitOpen 4:c233f2db4652 57 {
MikamiUitOpen 4:c233f2db4652 58 static int count = 0;
MikamiUitOpen 0:79c0b1e2fd10 59
MikamiUitOpen 4:c233f2db4652 60 xn_ = adc_->Read(); // AD変換器の値を読み込む
MikamiUitOpen 4:c233f2db4652 61 dac_.Write(buf_[ModIndex(indexR_)]); // 出力バッファの内容を DAC へ書き込む
MikamiUitOpen 0:79c0b1e2fd10 62
MikamiUitOpen 4:c233f2db4652 63 if (count == 0) // AD変換器からの入力信号は４回に１回使う
MikamiUitOpen 4:c233f2db4652 64 NVIC->STIR = CAN2_TX_IRQn; // ソフトウェア割込み発生，信号処理を起動
MikamiUitOpen 4:c233f2db4652 65 count = ++count & MASK_FACTOR_; // 入力を４回に１回行うための処理
MikamiUitOpen 4:c233f2db4652 66 }
MikamiUitOpen 0:79c0b1e2fd10 67
MikamiUitOpen 4:c233f2db4652 68 // 補間用 FIR フィルタ
MikamiUitOpen 4:c233f2db4652 69 float MultirateLiPh::Interpolator(const float hk[]) const
MikamiUitOpen 4:c233f2db4652 70 {
MikamiUitOpen 4:c233f2db4652 71 float y = 0;
MikamiUitOpen 4:c233f2db4652 72 for (int n=0; n<FIR_LOOP_; n++) y += un_[n]*hk[n];
MikamiUitOpen 4:c233f2db4652 73 return y;
MikamiUitOpen 4:c233f2db4652 74 }
MikamiUitOpen 0:79c0b1e2fd10 75
MikamiUitOpen 4:c233f2db4652 76 // ADC の初期化と割込み優先順位の設定
MikamiUitOpen 4:c233f2db4652 77 void MultirateLiPh::Init(float fSampling, PinName pin, ADC_TypeDef* const adc)
MikamiUitOpen 4:c233f2db4652 78 {
MikamiUitOpen 4:c233f2db4652 79 NVIC_SetPriority(ADC_IRQn, 0); // ADC 終了割り込み：最優先
MikamiUitOpen 4:c233f2db4652 80 NVIC_SetPriority(CAN2_TX_IRQn, 1); // ソフトウェア割り込みで使用：２番目に優先
MikamiUitOpen 3:59af3dfa0595 81
MikamiUitOpen 4:c233f2db4652 82 adc_ = new DspAdc_Intr(fSampling*FACTOR_, pin, adc);
MikamiUitOpen 4:c233f2db4652 83 }
MikamiUitOpen 3:59af3dfa0595 84
MikamiUitOpen 4:c233f2db4652 85 // static メンバの実体の宣言/初期化
MikamiUitOpen 4:c233f2db4652 86 DspAdc_Intr *MultirateLiPh::adc_; // AD変換器のオブジェクトのポインタ
MikamiUitOpen 4:c233f2db4652 87 DspDac MultirateLiPh::dac_; // DA変換器のオブジェクト
MikamiUitOpen 4:c233f2db4652 88 Array<float> MultirateLiPh::buf_(2*FACTOR_, 0.0f);
MikamiUitOpen 4:c233f2db4652 89 int MultirateLiPh::indexR_ = FACTOR_;
MikamiUitOpen 4:c233f2db4652 90 float MultirateLiPh::xn_;
MikamiUitOpen 4:c233f2db4652 91 }